1. Field of the Invention
This invention relates to a solid-state electrooptic shutter array element using the electrooptic effect.
2. Description of the Prior Art
Recently, with the development of information processing techniques, printers as output equipment for an information processing system have become important, and various types of printers are now being developed. Among them the optical printer, a kind of non-impact printer, is one of the most remarkable types. A device comprising electrooptic shutter elements utilizing the electrooptic effect arranged in an array is useful as the writing device for the optical printer.
As present, the well-known electrooptic shutter array element using electrooptic material is so constructed that a plurality of opposite strip electrodes are provided on a light-transmission substrate of lanthanum-modified lead zirconate titanate (PLZT) which has the composition of La/Zr/Ti=9/65/35 and shows a remarkable Kerr effect, and polarizing plates are disposed on the front and back surfaces of the substrate.
The principle of operation of the electrooptic shutter is that the opposite electrodes on the PLZT substrate are given a potential difference to create double refraction on the PLZT, thereby changing polarization of the incident light. The PLZT electrooptic shutter has a characteristic of high response speed and has hitherto been well studied. Some examples of the PLZT electrooptic shutter array are disclosed in "PLZT LINEAR ARRAY PAGE COMPOSER" by George R. Laguna, Pages 35 to 38, Ferroelectrics, Vol. 10 (1976), and Elektronik Industrie, Page 26, Vol. 6 (1980).
Such PLZT electrooptic shutter, however, has a large problem in that its transmittance varies greatly with a temperature variation.
On the other hand, in order to solve the above problem of the temperature characteristic, some improvements, have been disclosed in the Japanese Patent Application Laid-Open No. 59-135425, and "PLZT Electrooptic Shutter" by K. Tanaka, Pages 126 to 128, Supplement 22-2, Japanese Journal of Applied Physics Vol. 22 (1983).
The above problem, however, has not yet been solved properly, and therefore a practically usable electrooptic shutter has not yet been developed.